With advances in various technologies, electronic devices such as mobile terminals may provide not only basic functions including voice calls and text messages but also various supplementary functions including document handling, video editing and wireless Internet access. For convenience, some electronic devices have evolved into wearable devices that can be attached to human bodies.
Wearable devices may include wrist-attached devices such as a wristwatch or bracelet and head-mounted devices such as glasses and head-mounted display (HMD). A head-mounted display may comprise an image display device that enables a user to enjoy video content with a large screen experience. Head-mounted displays may also be applied to medical instruments usable for diagnosis or surgery. The electronic device embedded in a head-mounted display may display a first image on a display unit and, when a second image is received simultaneously display the first and second image on the display unit.
A Picture-in-Picture (PIP) feature is often used to simultaneously display two images, where a smaller image is superimposed in a small box form on a larger image. To realize superimposed images, a separate storage space is typically needed to store two original images and a PIP image produced therefrom. In addition, a combiner unit is conventionally used to combine the two original images in consideration of a desired position and size. Thus, a PIP feature typically utilizes device resources such as storage space, processing time, device power, and the like. A device capable of more efficiently displaying two images is therefore desirable.